If you drive in the UK, you know an MOT test is a legal necessity once your car is over three years old. It is all about safety, roadworthiness and making sure your vehicle meets emissions standards. Every year many cars fail their MOT, but a lot of those failures could be avoided with simple checks. Here are the top ten reasons cars fail their MOT tests and what you can do to avoid them.
1. Lighting & Signalling Problems
Lighting issues are the single most common cause of MOT failures. Around one quarter of tests fail because of faulty lamps, reflectors or electrical equipment. Problems include blown bulbs, cracked or misty lenses, issues with indicators, brake lights or registration plate lights. A quick walk around your car to check that all lights work, clean lenses and replace any bulbs you find suspect can save you from this common failure.
2. Suspension Faults
Suspension problems come up frequently in MOT tests. Worn shock absorbers or springs, loose joints, leaking components or uneven ride height all count. Rough or noisy handling over bumps or corners is a clue. You can press down on each corner of the car. If it does not settle properly, or if it bounces more than once, you may have a problem. Repairing suspension components before your test improves both safety and ride comfort.
3. Brakes
Brakes are obviously critical. MOT failures are often caused by worn pads, damaged or warped discs, poor brake balance (car pulling to one side), or even issues with the handbrake. Low brake fluid or leaks are also common culprits. If you notice squealing, grinding or uneven braking during use, get them checked. A car with faulty brakes will almost certainly fail.
4. Tyres
Tyres are the only part of the car in contact with the road, so their condition matters a lot. Common tyre-related MOT failures include tread below the legal minimum (1.6 mm across the central three quarters of the tread), cuts or bulges in the sidewalls, incorrect pressure or mismatched tyre sizes. Checking tyre tread and pressure regularly, especially before your MOT, will help prevent this failure.
5. Driver’s View of the Road / Visibility
Your view of the road must be clear and unobstructed. Failures in this area can include cracked or chipped windscreen (especially in the driver’s eyeline), worn or damaged wiper blades, blocked washers, mirrors missing or damaged, dirty windows or items hanging in the windscreen. Chips larger than a certain size or in the wrong area will lead to automatic failure. Ensuring your windscreen is clean, your wipers work well, and your mirrors are intact and correctly adjusted will help.
6. Exhaust, Emissions & Fuel System Issues
Vehicles must meet emissions standards and have exhaust systems that are leak-free and secure. Common problems include leaking exhausts, broken or inefficient catalytic converters, excessive emissions or loose components. Having your exhaust inspected, listening for unusual noises, ensuring no warning lights related to emissions are active, and repairing any leaks or faults before the MOT test will help.
7. Steering Faults
A car’s steering system must be sound and responsive. Issues that cause MOT failures here include excessive play in steering components, worn steering racks or joints, power steering system faults or fluid leaks. Odd noises when turning, wandering or poor handling are warning signs. Checking power steering fluid, looking for leaks and having any play checked by a professional will reduce the risk.
8. Bodywork & Structural Integrity
Rust or corrosion in load-bearing areas, loose or broken panels or bumpers, damage from previous accidents or anything that compromises the structure of the vehicle can lead to MOT failure. Especially for older vehicles, wheel arches, sills, undercarriage and chassis should be inspected. Repair or treat rust, ensure panels are secure and fix any loose body parts ahead of the test.
9. Seat Belts, Restraints & Safety Equipment
Safety features such as seat belts and airbags must be operational. Common problems are belts not retracting properly, damaged webbing, missing buckles or faulty anchorage. Airbag warning lights that stay on will also cause failure. Ensuring belts are clean, functional and properly fixed will help you avoid this area of failure.
10. Miscellaneous / Small Items
There are many smaller items that often lead to failures because drivers overlook them. These include registration plate issues (illegible or faded plates, plate lights not working), mirrors that are cracked or missing, horns that do not work, insecure bonnet or boot, warning lights on the dashboard and even interior lights. While individually minor, these can add up. Checking over every part of the car you can see, inside and out, before the MOT can pick up many of these issues.
What Happens If You Fail & What You Should Do
If your car fails its MOT test, you will receive a list of defects. Some are classed as major or dangerous. In those cases, the vehicle must be repaired before you can legally drive it, unless driving it directly for repairs or to a retest. Minor defects may be advisories, meaning you should fix them but they may not immediately stop you passing. It is illegal to drive a car that is unsafe or has dangerous faults.
You should review the failure report, get the repairs done, keep receipts and schedule a retest. In many cases you may get a partial or free retest if repairs are done within a fixed period and at the same test centre, so check the local rules.
Tips to Maximise Your Chances of Passing
Do a pre-MOT check yourself. Walk around the car, inspect lights, tyres, windscreen and mirrors. Listen for odd noises. Check fluid levels including brake fluid. Replace items that are cheap but likely to fail such as bulbs, wiper blades, washers and mirrors.
Keep your car well maintained year-round, not just before MOT time. Rust, corrosion and wear build up over time, so earlier intervention is more cost-effective.
Ensure your documentation is in order. Make sure tyres are fitted correctly, wheels aligned, safety features working and dashboard warning lights not on.
Conclusion
Many MOT failures are caused by simple, avoidable problems. With a few checks and small repairs, you can increase your chances of passing first time, save yourself time and money, and drive more safely. Take your vehicle seriously ahead of the test so that you know what to expect and avoid surprises.